Recent severe hotel fires have resulted in large numbers of people killed and injured. In addition to this problem, there are well known security problems arising from illegal entry into hotel rooms by burglars. Both of these problems have given rise to a need for a reliable portable intrusion and fire alarm apparatus that will warn the occupant not only of the existence of a fire in or close to his room, but also which will serve as an intrusion alarm in the case of unauthorized entry to the room. Such a unit must actuate audible alarm means to warn the occupant.
U.S. Pat. No. 2,552,331 issued to Lamb on May 8, 1951, discloses a portable electric alarm clock wherein an alarm means is automatically actuated when the temperature of the surrounding air reaches a predetermined value. U.S. Pat. No. 4,186,389 issued to Flittie on Jan. 29, 1980 discloses a similar arrangement, but uses a smoke detector instead of a temperature detector.
Such systems as disclosed in the latter of these patents, which employ a temperature sensor to warn the occupant of the existence of a fire, suffer from the disadvantage that the sensor does not sense the air temperature outside of the occupant's room but only that of the interior, the result being that by the time the temperature of the air in the room is sufficiently high to actuate the sensor and thereby warn the occupant, the fire outside the room door is frequently an impenetrable conflagration. Such devices suffer from a fundamental limitation that they sense the interior temperature of the room air, rather than producing a warning indicative of high air temperatures immediately outside the door to the room.
It is also commonly experienced that in the case of poorly fitting room doors, a substantial influx of combustion products containing toxic gases may penetrate the room to a dangerous level well advance of the rise of temperature outside of the room. It is thus desirable also that the portable alarm unit detect smoke in the room involved as well as a high temperature outside of it.
Prior art portable smoke and temperature detectors have not been heretofore associated with burglar alarms, so that the traveler does not have protection against entry of burglars into the hotel room involved.
In the most preferred form of the invention, there is incorporated into a single self-contained battery-powered unit of small size, all of the features just described.